When operating on patients, surgeons often need to accurately identify a region of interest, such as a disease region or a tumor, as well as the boundary of that region of interest. In some cases, such as when excising a tumor, a surrounding margin of healthy tissue around the tumor will be removed to ensure that no diseased tissue remains. When the boundary of the disease region cannot be robustly identified, excess healthy tissue may be removed unnecessarily, potentially leading to disability for the patient.
While intraoperative pathology methods exist to reveal some disease regions, there can be significant difficulties in distinguishing the disease regions from surrounding tissues, such as fatty breast tissues for example. Intraoperative pathology methods may also take upwards of 30 minutes to identify healthy and diseased tissue regions, leading to delays during surgery. In some cases, these delays and insufficiently robust identification of the disease region can lead to patients having to undergo subsequent surgeries to ensure that the entire disease region has been removed.
Imaging Mass Spectrometry (IMS) is one technique to map the chemical content of biological tissues in a spatially resolved manner. Recent developments in IMS techniques have opened up the prospect of intraoperative molecular imaging to identify disease states of tissues for effective diagnosis. These methods identify the tissue disease states on the basis of spatially mapping endogenous disease markers.
Desorption by Electrospray Ionization (DESI) MS imaging has been used to identify and grade tumor regions into their respective subclasses on the basis of endogenous lipid profiles unique to each tumor class. The endogenous lipid profiles typically require strong cross-validation with conventional pathology methods. Accordingly, the success of DESI-MS imaging and other current ambient IMS technologies in identifying a diseased region is heavily tied to the availability of validated molecular markers for the disease in question.